<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #tip{
            color: red;
        }
        .colFont{
            color: blue;
        }
        div{
            color: green;
        }
        #login form{
            color: red;
        }
    </style>
</head>
<body>
    <div id="tip" class="colFont" style="color:blueviolet;">我是一个程序员</div>
    <div id="login">
        <form action=""></form>
        <div class="a"></div>
        <div class="b"></div>
        <div class="c"></div>
        <div class="a"></div>
    </div>
    <div id="footer">
        <div class="a"></div>
        <div class="b"></div>
        <div class="c"></div>
        <div class="a"></div>
    </div>
</body>
</html>